trouble with D2

Blop

Blop

Joined
Mar 7, 2003
Messages
1,321
Hi forumites

i got a problem with my D2 edge. It´s a BM 806D2 model.

Nearly always, when i cut things harder then paper or like that, the edge becomes damagded. Meaning: little chips or it bends a bit.

I use a spyderco 204 sharpener, so i do not believe, the edge is to thin.

What is the reason? Any idea? Am i doing something wrong, or should i do something special, or is it probably material failure?
 
You have what's called a wire edge, where the edge is so fine that it seems very sharp at first, until it rolls. You need to strop the edge on leather, or keep using the white stones very lightly until all of the wire edge is removed. There's a lot better info on how that's done and can be found in the Sharpening FAQ, or by searching here.

Mike
 
It is rare to have a wire edge produce that kind of damage in use unless the steel is prone to large burrs, meaning it is soft and floppy, otherwise burrs are just a few microns in depth [unless ground on a grinding wheel or similar).

Unless of course the sharpening techinique was similar to sharpen just on one side, push really heavy on the corners until a burr was formed and just cut with that. This would produce a large burr and a very weak edge. However even minimal side switching would eliminate that problem.

It sounds like a junk blade to me, imperfections in the steel, or problems with the heat treatment. The steel could just be bad near the edge. Give it a full sharpening, say 50 passes per side on the coarse hone to completely reset the edge and move it back a bit and see if that helps.

-Cliff
 
The blade on my 806D2 has chipped only once before, when someone used it to cut the meat off of a chicken. The steel must have hit the fork.

For reference I use the 40 degree setting on my Sharpmaker for a secondary bevel. Cuts adequately well, no other problems with deformation or chipping. Sharpens more easily too, since I'm just hitting a thin strip of the blade to form the edge.

Are you sharpening at the 30 degree setting? Perhaps you should try 40.
 
Not so fast, the blades may not be junk. It could be hardening, or even unknown design features. Here are two cases:

One, my wife's Boa is so hard it chips like obsidian (volcanic glass), and I would hate to drop it. It looks like Crucible addressed this problem with heat-treating and the release of S90V.

Two, I just bought a Strider AR a few months ago. Lynn Little and I noticed tiny 'flat spots' on the edge, despite being careful with the Edge Pro and not dinging it, like on staples. The spots disappeared after a few sharpenings, but I first thought the folded blade was rubbing on a rivet. My new SnG has the same steel, but only one tiny spot has ever showed up; perhaps Paul Bos is becoming more familiar with this alloy.
 
Even fifteen degrees is easily obtuse enough unless you are cutting metal, I don't even run my heavy choppers at that high an angle. For most work you don't even need 15 degrees included.

By a junk blade, I didn't mean that particular brand, just that one specific knife. If the blade is performing as described with a proper sharpening it is junk as steels should be far more durable.

It isn't a hardness issue either, I have many blades at 62+ RC and while they are not heavy choppers, they can cut much more than paper, and none are ran at close to 22 degrees per side.

-Cliff
 
Cliff,

Maybe there ought to be some formula for alloy, degree of edge, distall taper and heat treat.

For example, a designer who likes S90V at 61 Rc might restrict his suggested edge to no more than 20 degrees. It might not have to be that strict, but automotive tires are rated by construction at a certain speed.

That said, I think the professional custom makers already know this from trial and error. But then, what do they say to a client who wants a CPM-440V at +64 Rc hunting knife sharpened below 15 degrees for use in wilderness camping for chopping?
 
Medic1210, thanks, i tried this yesterday, took long time, so today i´m not willing to test it. Hope, you´re right and the problem has gone. Even though, the decription of a wired edge, didn´t fit to my proplem, as far as my edge is not dull at these parts.

AlphalphaPB, i do it on 40°. Because i picked up this one for a bit rougher tasks.

Cliff Stamp, hope you´re not right, you understand? But i called to BM to get an opinion from them. I do agree, you should expect very much from D2, more than cutting paper.

Thanks Blop
 
Ichabod Poser :

... what do they say to a client who wants a CPM-440V at +64 Rc hunting knife sharpened below 15 degrees for use in wilderness camping for chopping?
Click to expand...

I would assume that it is fairly common for a user to ask something from a knife maker that they feel isn't practical as there are a lot of common knife myths and misconceptions. For example there is a lot of misinformation spread about hardness, for example SOG was promoting 64 RC BG-42 as very tough.

So what does a custom maker like R.J. Martin say when a user asks him for a large bush knife in BG-42 at 64 RC? Ask him. I would bet the answer would be that the steel would be far too brittle at that hardness [he already has said this on the forums]. There are lots of makers that don't over hype their products.

Blop :

Cliff Stamp, hope you´re not right
Click to expand...

The alternative is that the steel is fine, they expect it to behave that way, getting damaged on anything beyond paper and require 22+ degree angles. That isn't the standard of performance you should expect for that price of blade. But if you are willing to accept it, it is your money.

As I said, the first thing I would do is give it a full sharpening to insure that you are not just seeing weak steel at the edge. If this doesn't improve it, ask Benchmade if it is the expected behavior. If it isn't then get a replacement, if it is, then buy a Spyderco.

-Cliff
 
Just a point of clarification, Cliff. When you talk about 15 degrees included, do you mean 15 deg per side, or 15 deg total edge angle?

Thanks.
 
Included would be the total angle, so 7.5 degrees per side. Yes this sounds very low, but mainly because of the myth that 22 degrees per side is needed for general utility knives. This probably came out of the use of ultra brittle stainless steels for heavy use knives. Many of the current popular cutlery stainess steels have toughness many times to one lower than the tool, spring and carbon steels they replaced and far lower ductility levels as well as much more coarse grain structures.

On the wood cutters I use none of which are stainless steels (or high alloy steels), 15 degrees per side is where I generally set the lower end blades, machetes and the like. At this level they will handle all manner of woods well, and will take at most very slight damage on hard knots, dents like 0.010" thick at the back. High end knives made of better steel can take lower edge angles still :

http://www.bladeforums.com/forums/showthread.php?s=&threadid=215025

This isn't light tappy chopping either, it is full powered swings using shoulder drived swings, penetration will be 2"+ on clear pine.

If chopping isn't a requirement the edge angle can be set very low. My regular utility knives are set as low as I can grind them, generally from 5-10 degrees per side, so 10 to 20 degrees included. The notion that edge holding decreases as edge angle decreases is also a myth. It will increase many times over as long as the level of functional durability isn't lost, and for the majority of tasks this is very low. Consider just how soft most materials are compared to steel.

This isn't to say that 22 degree bevels or even more obtuse ones are not functional. I usually carry one knife with such a high edge angle which gets used to cut very hard materials or soft materials that are on hard materials, do scraping, edge prying etc. . I also usually microbevel the edges on my knives for ease of sharpening which does make the very edges significantly more obtuse, however this only extends to a depth of microns .

-Cliff
 
Interesting. My EDC is a CS Trailguide in Carbon V. I re-beveled it to 15 deg (included :D), and it does cut well. It does, however, impact readily when I'm whittling and hit a knot in the wood. It is very quick to sharpen, however...
 
Cliff,

so i did. I resharpened the edge and i´m very shure, there is no weak edge anymore. As i said, i´m not willing to test it today, maybe on the weekend. Medic might have been right, because the 204 is new to me and maybe i did to much intending to give the edge a touch up, in reality creating a wire edge.

I do expect much of this steel. Like Bob Dozier said: D2 holds its edge forever cutting cardbord but may dull quickly cutting bone or hardwood. He doesn´t say it will damage. I guess he produces very fine edges, he said pry bars could be produced by others.

So, if my testings do damage the edge, i believe, BM will replace the blade.
 
It really does sound like you've either got a bad blade, or the edge got too hot during factory sharpening. I've gotten a few knives that had wacky edges as you describe. Removing a bit of steel from the edges fixed these blades nicely.

D2 should not do as you've described, whether it be on cardboard or wood. D2 has exceptional edge holding characteristics when properly heat treated. I don't think I've ever had the edge roll on my Dozier K-4, and only hitting bone has managed to put miniscule sized chips in the blade.
 
I just spent about an hour rebeveling my 806D2 on a Sharpmaker, now the edge is at 30 degs included. The knife feels much sharper, plus it looks much better now that there's no secondary bevel.

I finally figured out why I have a flat spot on the edge about an edge from the tip. The backspacer has a little hump to accomodate the lanyard hole, and the knife sometimes slams into it. I sanded the hump just a little bit and pushed the backspacer out a bit, I hope this takes care of the problem. I've heard complaints about this happening in the linerlock AFCK's too.
 
swede79 :

[CS Trailguide in Carbon V at 15 degrees included]

It does, however, impact readily when I'm whittling and hit a knot in the wood.
Click to expand...

Yes, this is the price you pay for the cutting performance. Wood working blades in general were never expect to be able to handle hard cuts into knots without damage. Edge profiles were intentinally optomized for clear wood and the occasional bad knot could force a filing. In really bad situations, ring knots and such, often different axes were used.

For most lighter cutting you can solve the problem with a secondary bevel that is significantly more obtuse. It doesn't need to be very wide, not the full depth of the damage that is being seen. As long as the width is kept to a minimum the decrease to the cutting ability will be low.

Blop :

... if my testings do damage the edge, i believe, BM will replace the blade.
Click to expand...

I would hope so. With a proper sharpening, paper should not be the limit of the blades abilties. It doesn't matter if it is D2 or 1095 or ATS-34, even the low end cutlery steels like AISI-420 are much more durable than that.

-Cliff
 
I tested and finaly returned the knife.

Cliff and Medic and you all at this thread, thanks very much, you all helped me a lot.

Now it´s on the german BM dealer, to get this to an positive end (for me).
 
If the dealer gives any problems contact Benchmade directly and point them to this thread. It would be near insane for them to publically state that the expected performance of their blades, D2 or otherwise, would be to get damaged that easily.

-Cliff
 
Thanks Cliff,

i´m working as a real estate manager, so i´m used to waranty afairs, but not to the performance of steel grades.

As i see it now, the both, BM and the dealer, reacting quit o.k. BM responsed, that they see it as a bad blade, if it chipps like discripted, i informed the dealer about that, so he can´t stand behind this.

Result: It was the best, could happen to me, to ask around here and get the feed back as everybody can see above.

Blop
 
So, the story came to a "happy end".

The Benchmade warranty- dep. sended a new knife, it arrived postage free today. I hadn´t to send the failed knife back to BM, it was just enough to give it back to the local dealer.

BM warrant-dep.: Very friendly and they trusted my words without question.

The knife came sharp out of the box, fit and finish super, and it cuts without my former trouble.

Just one thing: Waiting for it was harder than waiting for christmas child (same function as st. claus) in my childhood.

Blop
 
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